1/* 2 * DivX (XSUB) subtitle encoder 3 * Copyright (c) 2005 DivX, Inc. 4 * Copyright (c) 2009 Bjorn Axelsson 5 * 6 * This file is part of Libav. 7 * 8 * Libav is free software; you can redistribute it and/or 9 * modify it under the terms of the GNU Lesser General Public 10 * License as published by the Free Software Foundation; either 11 * version 2.1 of the License, or (at your option) any later version. 12 * 13 * Libav is distributed in the hope that it will be useful, 14 * but WITHOUT ANY WARRANTY; without even the implied warranty of 15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 16 * Lesser General Public License for more details. 17 * 18 * You should have received a copy of the GNU Lesser General Public 19 * License along with Libav; if not, write to the Free Software 20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 21 */ 22 23#include "avcodec.h" 24#include "bytestream.h" 25#include "put_bits.h" 26 27/** 28 * Number of pixels to pad left and right. 29 * 30 * The official encoder pads the subtitles with two pixels on either side, 31 * but until we find out why, we won't do it (we will pad to have width 32 * divisible by 2 though). 33 */ 34#define PADDING 0 35#define PADDING_COLOR 0 36 37/** 38 * Encode a single color run. At most 16 bits will be used. 39 * @param len length of the run, values > 255 mean "until end of line", may not be < 0. 40 * @param color color to encode, only the lowest two bits are used and all others must be 0. 41 */ 42static void put_xsub_rle(PutBitContext *pb, int len, int color) 43{ 44 if (len <= 255) 45 put_bits(pb, 2 + ((ff_log2_tab[len] >> 1) << 2), len); 46 else 47 put_bits(pb, 14, 0); 48 put_bits(pb, 2, color); 49} 50 51/** 52 * Encode a 4-color bitmap with XSUB rle. 53 * 54 * The encoded bitmap may be wider than the source bitmap due to padding. 55 */ 56static int xsub_encode_rle(PutBitContext *pb, const uint8_t *bitmap, 57 int linesize, int w, int h) 58{ 59 int x0, x1, y, len, color = PADDING_COLOR; 60 61 for (y = 0; y < h; y++) { 62 x0 = 0; 63 while (x0 < w) { 64 // Make sure we have enough room for at least one run and padding 65 if (pb->size_in_bits - put_bits_count(pb) < 7*8) 66 return -1; 67 68 x1 = x0; 69 color = bitmap[x1++] & 3; 70 while (x1 < w && (bitmap[x1] & 3) == color) 71 x1++; 72 len = x1 - x0; 73 if (PADDING && x0 == 0) { 74 if (color == PADDING_COLOR) { 75 len += PADDING; 76 x0 -= PADDING; 77 } else 78 put_xsub_rle(pb, PADDING, PADDING_COLOR); 79 } 80 81 // Run can't be longer than 255, unless it is the rest of a row 82 if (x1 == w && color == PADDING_COLOR) { 83 len += PADDING + (w&1); 84 } else 85 len = FFMIN(len, 255); 86 put_xsub_rle(pb, len, color); 87 88 x0 += len; 89 } 90 if (color != PADDING_COLOR && (PADDING + (w&1))) 91 put_xsub_rle(pb, PADDING + (w&1), PADDING_COLOR); 92 93 avpriv_align_put_bits(pb); 94 95 bitmap += linesize; 96 } 97 98 return 0; 99} 100 101static int make_tc(uint64_t ms, int *tc) 102{ 103 static const int tc_divs[3] = { 1000, 60, 60 }; 104 int i; 105 for (i=0; i<3; i++) { 106 tc[i] = ms % tc_divs[i]; 107 ms /= tc_divs[i]; 108 } 109 tc[3] = ms; 110 return ms > 99; 111} 112 113static int xsub_encode(AVCodecContext *avctx, unsigned char *buf, 114 int bufsize, void *data) 115{ 116 AVSubtitle *h = data; 117 uint64_t startTime = h->pts / 1000; // FIXME: need better solution... 118 uint64_t endTime = startTime + h->end_display_time - h->start_display_time; 119 int start_tc[4], end_tc[4]; 120 uint8_t *hdr = buf + 27; // Point behind the timestamp 121 uint8_t *rlelenptr; 122 uint16_t width, height; 123 int i; 124 PutBitContext pb; 125 126 if (bufsize < 27 + 7*2 + 4*3) { 127 av_log(avctx, AV_LOG_ERROR, "Buffer too small for XSUB header.\n"); 128 return -1; 129 } 130 131 // TODO: support multiple rects 132 if (h->num_rects > 1) 133 av_log(avctx, AV_LOG_WARNING, "Only single rects supported (%d in subtitle.)\n", h->num_rects); 134 135 // TODO: render text-based subtitles into bitmaps 136 if (!h->rects[0]->pict.data[0] || !h->rects[0]->pict.data[1]) { 137 av_log(avctx, AV_LOG_WARNING, "No subtitle bitmap available.\n"); 138 return -1; 139 } 140 141 // TODO: color reduction, similar to dvdsub encoder 142 if (h->rects[0]->nb_colors > 4) 143 av_log(avctx, AV_LOG_WARNING, "No more than 4 subtitle colors supported (%d found.)\n", h->rects[0]->nb_colors); 144 145 // TODO: Palette swapping if color zero is not transparent 146 if (((uint32_t *)h->rects[0]->pict.data[1])[0] & 0xff) 147 av_log(avctx, AV_LOG_WARNING, "Color index 0 is not transparent. Transparency will be messed up.\n"); 148 149 if (make_tc(startTime, start_tc) || make_tc(endTime, end_tc)) { 150 av_log(avctx, AV_LOG_WARNING, "Time code >= 100 hours.\n"); 151 return -1; 152 } 153 154 snprintf(buf, 28, 155 "[%02d:%02d:%02d.%03d-%02d:%02d:%02d.%03d]", 156 start_tc[3], start_tc[2], start_tc[1], start_tc[0], 157 end_tc[3], end_tc[2], end_tc[1], end_tc[0]); 158 159 // Width and height must probably be multiples of 2. 160 // 2 pixels required on either side of subtitle. 161 // Possibly due to limitations of hardware renderers. 162 // TODO: check if the bitmap is already padded 163 width = FFALIGN(h->rects[0]->w, 2) + PADDING * 2; 164 height = FFALIGN(h->rects[0]->h, 2); 165 166 bytestream_put_le16(&hdr, width); 167 bytestream_put_le16(&hdr, height); 168 bytestream_put_le16(&hdr, h->rects[0]->x); 169 bytestream_put_le16(&hdr, h->rects[0]->y); 170 bytestream_put_le16(&hdr, h->rects[0]->x + width); 171 bytestream_put_le16(&hdr, h->rects[0]->y + height); 172 173 rlelenptr = hdr; // Will store length of first field here later. 174 hdr+=2; 175 176 // Palette 177 for (i=0; i<4; i++) 178 bytestream_put_be24(&hdr, ((uint32_t *)h->rects[0]->pict.data[1])[i]); 179 180 // Bitmap 181 // RLE buffer. Reserve 2 bytes for possible padding after the last row. 182 init_put_bits(&pb, hdr, bufsize - (hdr - buf) - 2); 183 if (xsub_encode_rle(&pb, h->rects[0]->pict.data[0], 184 h->rects[0]->pict.linesize[0]*2, 185 h->rects[0]->w, (h->rects[0]->h + 1) >> 1)) 186 return -1; 187 bytestream_put_le16(&rlelenptr, put_bits_count(&pb) >> 3); // Length of first field 188 189 if (xsub_encode_rle(&pb, h->rects[0]->pict.data[0] + h->rects[0]->pict.linesize[0], 190 h->rects[0]->pict.linesize[0]*2, 191 h->rects[0]->w, h->rects[0]->h >> 1)) 192 return -1; 193 194 // Enforce total height to be be multiple of 2 195 if (h->rects[0]->h & 1) { 196 put_xsub_rle(&pb, h->rects[0]->w, PADDING_COLOR); 197 avpriv_align_put_bits(&pb); 198 } 199 200 flush_put_bits(&pb); 201 202 return hdr - buf + put_bits_count(&pb)/8; 203} 204 205static av_cold int xsub_encoder_init(AVCodecContext *avctx) 206{ 207 if (!avctx->codec_tag) 208 avctx->codec_tag = MKTAG('D','X','S','B'); 209 210 return 0; 211} 212 213AVCodec ff_xsub_encoder = { 214 .name = "xsub", 215 .type = AVMEDIA_TYPE_SUBTITLE, 216 .id = CODEC_ID_XSUB, 217 .init = xsub_encoder_init, 218 .encode = xsub_encode, 219 .long_name = NULL_IF_CONFIG_SMALL("DivX subtitles (XSUB)"), 220}; 221